The subject matter disclosed herein relates generally to electric machines. More specifically, the subject disclosure relates to permanent magnet rotor construction for electric machines.
Typical permanent magnet rotors used in electric machines, such as hybrid motors, include slots extending through a rotor lamination stack to receive the permanent magnets. The slots are typically oval in shape, and receive rectangular magnets, so there are gaps between each slot and each magnet. This gap is then injected molded with nylon or filled with an epoxy or varnish material to fill the gap.
Cooling the permanent magnets in such a rotor is a challenge. Operation of the rotor at elevated temperatures causes degradation in magnet performance, and even demagnetization of the magnets resulting in failure of the motor.